To make a high density position detection possible to be carried out at a low cost, by installing a magnet at a moving part and also installing a plurality of Hall elements for magnet-proximity detection along the moving range.
Immediately after the power supply of an apparatus is turned on, a control part 7 confirms the state of respective Hall elements 5a, 5b, 5c. When, e.g. the Hall element 5b is in an ON state, the control part 7 judges that a moving part 3 is situated in the center. When the control part 7 judges that all the Hall elements 5a to 5c are in an OFF state, the control part 7 sends out pulses to a pulse motor 1, it moves the moving part 3, and it confirms that the state of the respective Hall elements 5a, 5b, 5c is changed. For example, when the moving part 3 is situated between the Hall elements 5b, 5c, the Hall element 5b is soon set to an ON state, and it is detected that the moving part 3 is situated in the center. When the moving part 3 is situated between the Hall elements 5a, 5b, the Hall element 5a is soon sent to an ON state, and it is detected that the moving part 3 is situated at the shaft end on the side of the pulse motor 1.
Amano, Taro
Shin, Yasuo
Sakai, Katsuhide
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